Field of the Disclosure
The disclosure relates to a network system, and particularly relates to an optical data center network system and an optical switch.
Description of Related Art
Data center networks (DCNs) have been designed to provide reliable and efficient network infrastructure for a data center to support a wide variety of today's cloud or enterprise applications and services, e.g., grid/cloud computing, data storage, data mining and social networking, etc. Evidence shows that these applications/services not only involve much client-server (i.e., north-south) traffic flowing in and out within DCNs, but also spawn a massive amount of east-west server-to-server traffic within DCNs. These applications and services are data rich by nature, and demand high bandwidth and low latency transport of data. Besides, recent studies have further shown an ever-growing trend toward the variety and complexity of new cloud or enterprise applications and services. Such trend places a higher demand for large-scale DCN that can deliver substantially high bandwidth, low latency/jitter and reduced power consumption. For large-scale DCNs, there has been an increasing tendency towards modular design. The module-oriented data center can be constructed from purpose-engineered modules, e.g., pods or containers, which can be flexibly expanded to the original data center infrastructure in an architecture complaint manner. Besides, it is of crucial importance for future DCNs to adopt incremental design. The incremental design allows a rollout and seamless expansion, resulting in agile and economical deployment and delivering resources on fully as-needed basis.
Current DCNs architectures can be distinguished according to whether an all-optical switch is adopted, where the DCN architectures without the all-optical switch generally still apply an electrical switch for data switching. Although the DCN architectures applying the electrical switch adopt optical fibers to transmit data between the switches, a transmission rate thereof is still limited by the electrical switch. Moreover, during a data transmission process, a photoelectric converter has to be used to implement multiple optical-to-electrical conversions or electrical-to-optical conversions, which causes a large power consumption. Moreover, since the number of input/output ports of the electrical switch is limited, and one optical fiber can only contain one wavelength band, the number of cables used for network connection is huge, which greatly increases a degree of difficulty in deployment and maintenance, and accordingly increases difficulty in network expansion.
In order to resolve the above problems, related literatures provide a plurality of photoelectric mixed architectures and full optical architectures. The photoelectric mixed architecture still has the problem of electrical-to-optical conversion, so that the problem in power consumption is not effectively resolved. Comparatively, the full optical architecture does not switch data through electricity, so that power consumption in electrical-to-optical conversion is greatly decreased. For example, in a double tier annular wavelength division multiplexing (WDM) optical data center network architecture, only two nodes located at the head and tail in the annular network are connected to the nodes of a previous tier, and if a signal is to be transmitted to a certain node in a different annular architecture, the signal has to pass through the nodes at the head and tail in the two annular networks, and is then sequentially transmitted to a designation through an annular manner, which can cause a large latency. Moreover, a connection port of a WDM add/drop module used in the architecture corresponds to a fixed wavelength, which greatly limits a path selection capability between the servers in the architecture. In addition, the architecture is only designed to accommodate the switching nodes of two tiers, and if the architecture is to be extended, only the number of the nodes of the first two tiers can be increased. However, if excessive nodes are used in the ring of the same tier, it may cause a high latency, which seriously limits scalability of the architecture.
Another DCN architecture includes tunable optical transceivers, tunable wavelength converters (TWCs), arrayed waveguide grating routers (AWGRs), buffer registers, etc., where the tunable optical transceivers are expensive, and the buffer registers are electric components other than optical components, which requires electrical-to-optical conversion so that data could be stored in temporarily. Moreover, system scalability of such DCN architecture is limited by the number of connection ports of the AWGRs, so that the scalability thereof is poor.
One DCN architecture adopts a micro-electro-mechanical system (MEMS) to ensure a direct connection between top of rack (ToR) switches, which causes the high path-configuration complexity. Moreover, several milliseconds generally are required for the reconfiguration time of the MEMS paths, which sets a limit on the switching time for the DCN. In summary, the existing DCN architectures can only resolve or satisfy a part of bottlenecks and demands of the full-optical-switching systems.